1. Field of the Invention
The present invention relates to an anti-stress composition comprising astaxanthin and/or its ester, and a food or beverage to which it is added. More specifically, the present invention relates to a composition for preventing or alleviating decreased immunological function, decreased liver function and fatigue caused by stress as well as those medical conditions due to decreased immunological function caused by stress such as cancer metastasis, comprising astaxanthin and/or its ester, and to a food or beverage prepared by adding said composition to a food or beverage material that essentially does not contain astaxanthin and/or its ester.
2. Related Art
Stress is quite prevalent in modern society, and those diseases caused by stress, namely somatic disorders as well as stress disorders such as neurosis and depression, are increasing. Stress disorders and other related disorders are believed to comprise a condition in which stress destroys the ability to maintain homeostasis by the body. Alleviation and treatment of these disorders consists of nosotropic therapy for each symptom and disease.
In addition, drugs such as antianxiety agents and sleeping pills for temporarily alleviating somatic reactions when exposed to stress are considered to be an effective means of dealing with stress. However, there are no known drugs that are able to fundamentally inhibit or reduce stress. Moreover, various relaxation techniques for the mind and body have been proposed as ways of effectively controlling stress so prevent destruction of the body's homeostasis. However, long-term efforts will most likely be required due to personal differences and other factors.
In addition, various drugs and foods have been developed for the purpose of preventing and reducing stress or fatigue. Typical examples of these include sports drinks and tonics. Sports drinks have a rapid moisture absorption rate and are intended to rapidly supplement vitamins, amino acids and minerals lost due to perspiration. They do not prevent or reduce stress and fatigue directly. Tonics, on the other hand, contain extracts from several medical plants in addition to vitamins and amino acids. These are expected to have physiological effects such as central nervous system stimulation, increased blood flow, cardiac effects and activation of endocrine system. However, many of the physiological effects of these natural drugs are based on old legends, and none are known, on a scientific basis, to prevent or reduce stress.
More recently, there have been numerous reports which stated that stress, affliction and numerous mental disorders are all pronounced emotional disorders, indicating research results that show that these disorders are closely linked with decreased immunological function of the body. Although the concept of mental anguish being a cause of illness is itself quite old, only recently has attention been focused on this concept in scientific fields as well. Considerable immunological research has been conducted on the relationship between stress and cancer in particular. However, there are no known specific compounds that inhibit the onset and metastasis of cancer caused by stress.
Astaxanthin is one of secondary carotenoids, and is present in animals such as crustaceans including krill, shrimp and crabs, the muscle and eggs of salmon and trout, and the body surfaces of sea bream, carp and goldfish.
At present, although astaxanthin is used as a color restorer for cultured fish such as sea bream, salmon, trout and yellowtail, recent research has clearly shown that astaxanthin can become provitamin A as well as demonstrate remarkable antioxidative effects. It is thus expected to be used in natural coloring agents, antioxidants, nutritional supplements, cosmetics and pharmaceuticals [Yamashita, E: Food and Development, Vol. 27, No. 3 (Consecutive Volume No. 409), p. 38-40 (1992)]. In addition, Japanese Unexamined Patent Publication No. 63-83017 discloses a sunburn-preventive cosmetic containing astaxanthin, while Japanese Unexamined Patent Publication No. 2-49091 discloses an antioxidant having astaxanthin for its active ingredient along with a pharmaceutical and an antiphlogistic for defending against oxidative tissue disorders of the body.
In addition, astaxanthin is also known to have cancer cell growth inhibitory activity [Carotenoids of Marine Life (Miki, W. ed.), p.105-113, Koseisha, Koseikaku (April 1993)] and antibody production activity [H. Jyonouchi et al., Nutrition and Cancer, Vol. 19, No. 3, p. 269-280 (1993)].
However, astaxanthin is not known to have anti-stress effects or be effective in the prevention or alleviation of decreased immunological function, decreased liver function and fatigue.